CO2-SR technology using NiBa unsupported catalyst. Isotopic study of cyclic process of CO2 storage and in situ regeneration with CH4

The unsupported NiBa catalyst has been used in the CO2-SR (CO2 Storage and in situ Regeneration with CH4) cyclic technology, which allows the use of CO2 from combustion and CH4 from biogas in order to produce enriched syngas streams. The isotopic study in transient regime, using 13CO2 and CD4 instead of 12CO2 and CH4, respectively, has been performed to discriminate the different carbon and hydrogen sources and the participation of the catalyst in the pathways involved in the whole cyclic process of the integrated capture of CO2 and the regeneration with CH4. The dual functionality of the catalyst showed a high chemical retention capacity of CO2 (around 0.15 mmol CO2⋅gcat-1 ) in basic Ni-Ba intermetallic centers together with the regeneration capacity through the injection of methane yielding to H2-containing stream production. During the storage stage, the CO2 adsorption and dissociative decomposition are the main reactions together with Boudouard reaction, whereas in the regeneration step, syngas was formed via chemical CO2 reduction by CH4, besides dry methane reforming.Funding for open access charge: Universidad de Malaga ´ / CBU

An ultraviolet-visible-near infrared study of the electronic structure of oxide-supported vanadia-tungsta and vanadia-molybdena

none2The ultraviolet-visible-near IR spectra of a series of catalysts have been recorded and discussed. In particular bulk and alumina-, titania- and silica-supported V, W, and Mo oxides have been considered. Additionally mixed V-W and V-Mo-supported oxides have been investigated. The data show that, in agreement with vibrational data and other literature data, the oxides supported on silica are similar to the corresponding bulk oxides. In contrast, the spectra of the oxides supported on alumina and titania correspond to surface oxide species where the metal stays in a lower overall coordination with respect to the bulk oxides. Finally, the spectra show that only in the case of titania-supported oxides an electronic interaction between the supported metal oxide centers through the support conduction band is possible. This allows to justify on electronic bases the activating effect of titania for vanadia, vanadia-tungsta and vanadia-molybdena catalysts used in the hydrocarbon selective oxidation catalysis and for the selective catalytic reduction of nitrogen oxide by ammonia. (C) 2001 Elsevier Science B.V. All rights reserved.M. A. Larrubia;G. BuscaM. A., Larrubia; Busca, Guid

Removal of Phenol from Aqueous Solution by Adsorption on to Coal Fly Ash

The present work examines the possible use of fly ash, a byproduct of coal power stations, as a means of removing phenol from water, or equivalently, of restricting its movement in solid wastes or soil. Equilibrium experiments were performed to evaluate the removal efficiency of fly ash. The adsorption experiments were undertaken using fly ash treated at three different pH levels and with three different temperatures. The results indicate that although phenol can be removed from water, this depends markedly on the temperature and pH value of the treatment solution employed

Characterization of alumina-supported Pt, Ni and PtNi alloy catalysts for the dry reforming of methane

Two bimetallic PtNi catalysts supported on a nanostructured c-Al2O3 together with the corresponding monometallic materials, employed for the dry reforming of methane, have been prepared and characterized. Characterization of the catalysts, in reduced form, has been performed by FTIR spectroscopy of adsorbed carbon monoxide at low and room temperature. XRD, TEM and XPS analysis have also been performed. IR spectra of adsorbed CO indicate that the surface of the PtNi catalysts is dominated by Pt centers, whose electron-withdrawing character is increased by Ni. It has also been confirmed the formation of PtNi alloy, which is enriched at the surface by Pt and has smaller metal crystal size than metal particles in monometallic Pt and Ni catalysts. The alloy formation is associated with higher activity and lower production of carbonaceous materials upon dry reforming of methane